Lucy Brown collapsed after she was struck in the head during a routine sparring match at Wellsford Boxing Sport and Fitness Club at Centennial Park, north of Auckland, on August 8, Stuff.co.nz reported.

It's believed the 31-year-old stepped out of the ring to get a drink of water after the incident but then fell unconscious after saying she felt unwell.

Auckland Westpac Rescue Helicopter intensive care flight paramedic, Russell Clarke, was one of the first medics on the scene at around 11.30am on Saturday.

He said it was obvious Ms Brown had sustained a concussion in the ring and she deteriorated from there.

'When she got out of the ring, she had a drink of water and some paracetamol because she didn't feel quite right and then she collapsed sometime afterwards,' he said.

Auckland City Police detective senior sergeant Lloyd Scmid told the publication a woman was airlifted to Auckland City Hospital in a critical condition after she felt unwell but she later died on August 22 - he didn't confirm the woman's identity.

Ms Brown, who was diagnosed with stage three cervical cancer in 2011, had only recently moved back to New Zealand after living in Townsville for a number of years.

After surviving her cancer battle, she enrolled in a boxing class at her local gym to get in shape - but her passion for the ring led to her losing half of her body weight.